Looking for a 'cmake clean' command to clear up CMake output

CMake 3.X

CMake 3.X offers a 'clean' target.

cmake --build C:/foo/build/ --target clean

From the CMake docs for 3.0.2:

--clean-first  = Build target 'clean' first, then build.
                 (To clean only, use --target 'clean'.)

CMake 2.X

There is no cmake clean in CMake version 2.X

I usually build the project in a single folder like "build". So if I want to make clean, I can just rm -rf build.

The "build" folder in the same directory as the root "CMakeLists.txt" is usually a good choice. To build your project, you simply give cmake the location of the CMakeLists.txt as an argument. For example: cd <location-of-cmakelists>/build && cmake ... (From @ComicSansMS)

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CMake official FAQ states:

Some build trees created with GNU autotools have a "make distclean" target that cleans the build and also removes Makefiles and other parts of the generated build system. CMake does not generate a "make distclean" target because CMakeLists.txt files can run scripts and arbitrary commands; CMake has no way of tracking exactly which files are generated as part of running CMake. Providing a distclean target would give users the false impression that it would work as expected. (CMake does generate a "make clean" target to remove files generated by the compiler and linker.) A "make distclean" target is only necessary if the user performs an in-source build. CMake supports in-source builds, but we strongly encourage users to adopt the notion of an out-of-source build. Using a build tree that is separate from the source tree will prevent CMake from generating any files in the source tree. Because CMake does not change the source tree, there is no need for a distclean target. One can start a fresh build by deleting the build tree or creating a separate build tree.

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In these days of Git everywhere, you may forget CMake and use git clean -d -f -x, that will remove all files not under source control.

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I googled it for like half an hour and the only useful thing I came up with was invoking the find utility:

# Find and then delete all files under current directory (.) that:
#  1. contains "cmake" (case-&insensitive) in its path (wholename)
#  2. name is not CMakeLists.txt
find . -iwholename '*cmake*' -not -name CMakeLists.txt -delete

Also, be sure to invoke make clean (or whatever CMake generator you're using) before that.

:)

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You can use something like:

add_custom_target(clean-cmake-files
   COMMAND ${CMAKE_COMMAND} -P clean-all.cmake
)

// clean-all.cmake
set(cmake_generated ${CMAKE_BINARY_DIR}/CMakeCache.txt
                    ${CMAKE_BINARY_DIR}/cmake_install.cmake
                    ${CMAKE_BINARY_DIR}/Makefile
                    ${CMAKE_BINARY_DIR}/CMakeFiles
)

foreach(file ${cmake_generated})

  if (EXISTS ${file})
     file(REMOVE_RECURSE ${file})
  endif()

endforeach(file)

I usually create a "make clean-all" command adding a call to "make clean" to the previous example:

add_custom_target(clean-all
   COMMAND ${CMAKE_BUILD_TOOL} clean
   COMMAND ${CMAKE_COMMAND} -P clean-all.cmake
)

Don't try to add the "clean" target as a dependence:

add_custom_target(clean-all
   COMMAND ${CMAKE_COMMAND} -P clean-all.cmake
   DEPENDS clean
)

Because "clean" isn't a real target in CMake and this doesn't work.

Moreover, you should not use this "clean-cmake-files" as dependence of anything:

add_custom_target(clean-all
   COMMAND ${CMAKE_BUILD_TOOL} clean
   DEPENDS clean-cmake-files
)

Because, if you do that, all CMake files will be erased before clean-all is complete, and make will throw you an error searching "CMakeFiles/clean-all.dir/build.make". In consequence, you can not use the clean-all command before "anything" in any context:

add_custom_target(clean-all
   COMMAND ${CMAKE_BUILD_TOOL} clean
   COMMAND ${CMAKE_COMMAND} -P clean-all.cmake
)

That doesn't work either.

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Simply issuing rm CMakeCache.txt works for me too.

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Maybe it's a little outdated, but since this is the first hit when you google cmake clean, I will add this:

Since you can start a build in the build dir with a specified target with

cmake --build . --target xyz

you can of course run

cmake --build . --target clean

to run the clean target in the generated build files.

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I agree that the out-of-source build is the best answer. But for the times when you just must do an in-source build, I have written a Python script available here, which:

Runs "make clean" Removes specific CMake-generated files in the top-level directory such as CMakeCache.txt For each subdirectory that contains a CMakeFiles directory, it removes CMakeFiles, Makefile, cmake_install.cmake. Removes all empty subdirectories.

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It's funny to see this question gets so many attentions and complicated solutions, which indeed shows a pain to not have a clean method with cmake.

Well, you can definitely cd build_work to do you work, then do a rm -rf * when you need to clean. However, rm -rf * is a dangerous command given that many people are often not aware which dir they are in.

If you cd .., rm -rf build_work and then mkdir build_work and then cd build_work, that's just too much typing.

So a good solution is to just stay out of the build folder and tell cmake the path:
to configure: cmake -B build_work
to build: cmake --build build_work
to install: cmake --install build_work
to clean: rm -rf build_work
to recreate build folder: you don't even need mkdir build_work, just configure it with cmake -B build_work.

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In the case where you pass -D parameters into CMake when generating the build files and don't want to delete the entire build/ directory:

Simply delete the CMakeFiles/ directory inside your build directory.

rm -rf CMakeFiles/
cmake --build .

This causes CMake to rerun, and build system files are regenerated. Your build will also start from scratch.

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Of course, out-of-source builds are the go-to method for Unix Makefiles, but if you're using another generator such as Eclipse CDT, it prefers you to build in-source. In which case, you'll need to purge the CMake files manually. Try this:

find . -name 'CMakeCache.txt' -o -name '*.cmake' -o -name 'Makefile' -o -name 'CMakeFiles' -exec rm -rf {} +

Or if you've enabled globstar with shopt -s globstar, try this less disgusting approach instead:

rm -rf **/CMakeCache.txt **/*.cmake **/Makefile **/CMakeFiles

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try to use: cmake --clean-first path-of-CMakeLists.txt-file -B output-dir

--clean-first: Build target clean first, then build. (To clean only, use --target clean.)

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A solution that I found recently is to combine the out-of-source build concept with a Makefile wrapper.

In my top-level CMakeLists.txt file, I include the following to prevent in-source builds:

if ( ${CMAKE_SOURCE_DIR} STREQUAL ${CMAKE_BINARY_DIR} )
    message( FATAL_ERROR "In-source builds not allowed. Please make a new directory (called a build directory) and run CMake from there. You may need to remove CMakeCache.txt." )
endif()

Then, I create a top-level Makefile, and include the following:

# -----------------------------------------------------------------------------
# CMake project wrapper Makefile ----------------------------------------------
# -----------------------------------------------------------------------------

SHELL := /bin/bash
RM    := rm -rf
MKDIR := mkdir -p

all: ./build/Makefile
    @ $(MAKE) -C build

./build/Makefile:
    @  ($(MKDIR) build > /dev/null)
    @  (cd build > /dev/null 2>&1 && cmake ..)

distclean:
    @  ($(MKDIR) build > /dev/null)
    @  (cd build > /dev/null 2>&1 && cmake .. > /dev/null 2>&1)
    @- $(MAKE) --silent -C build clean || true
    @- $(RM) ./build/Makefile
    @- $(RM) ./build/src
    @- $(RM) ./build/test
    @- $(RM) ./build/CMake*
    @- $(RM) ./build/cmake.*
    @- $(RM) ./build/*.cmake
    @- $(RM) ./build/*.txt

ifeq ($(findstring distclean,$(MAKECMDGOALS)),)
    $(MAKECMDGOALS): ./build/Makefile
    @ $(MAKE) -C build $(MAKECMDGOALS)
endif

The default target all is called by typing make, and invokes the target ./build/Makefile.

The first thing the target ./build/Makefile does is to create the build directory using $(MKDIR), which is a variable for mkdir -p. The directory build is where we will perform our out-of-source build. We provide the argument -p to ensure that mkdir does not scream at us for trying to create a directory that may already exist.

The second thing the target ./build/Makefile does is to change directories to the build directory and invoke cmake.

Back to the all target, we invoke $(MAKE) -C build, where $(MAKE) is a Makefile variable automatically generated for make. make -C changes the directory before doing anything. Therefore, using $(MAKE) -C build is equivalent to doing cd build; make.

To summarize, calling this Makefile wrapper with make all or make is equivalent to doing:

mkdir build
cd build
cmake ..
make 

The target distclean invokes cmake .., then make -C build clean, and finally, removes all contents from the build directory. I believe this is exactly what you requested in your question.

The last piece of the Makefile evaluates if the user-provided target is or is not distclean. If not, it will change directories to build before invoking it. This is very powerful because the user can type, for example, make clean, and the Makefile will transform that into an equivalent of cd build; make clean.

In conclusion, this Makefile wrapper, in combination with a mandatory out-of-source build CMake configuration, make it so that the user never has to interact with the command cmake. This solution also provides an elegant method to remove all CMake output files from the build directory.

P.S. In the Makefile, we use the prefix @ to suppress the output from a shell command, and the prefix @- to ignore errors from a shell command. When using rm as part of the distclean target, the command will return an error if the files do not exist (they may have been deleted already using the command line with rm -rf build, or they were never generated in the first place). This return error will force our Makefile to exit. We use the prefix @- to prevent that. It is acceptable if a file was removed already; we want our Makefile to keep going and remove the rest.

Another thing to note: This Makefile may not work if you use a variable number of CMake variables to build your project, for example, cmake .. -DSOMEBUILDSUSETHIS:STRING="foo" -DSOMEOTHERBUILDSUSETHISTOO:STRING="bar". This Makefile assumes you invoke CMake in a consistent way, either by typing cmake .. or by providing cmake a consistent number of arguments (that you can include in your Makefile).

Finally, credit where credit is due. This Makefile wrapper was adapted from the Makefile provided by the C++ Application Project Template.

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I use the following shell script for such purposes:

#!/bin/bash

for fld in $(find -name "CMakeLists.txt" -printf '%h ')
do
    for cmakefile in CMakeCache.txt cmake_install.cmake CTestTestfile.cmake CMakeFiles Makefile
    do
        rm -rfv $fld/$cmakefile
    done
done

If you are using Windows then use Cygwin for this script.

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To simplify cleaning when using "out of source" build (i.e. you build in the build directory), I use the following script:

$ cat ~/bin/cmake-clean-build
#!/bin/bash

if [ -d ../build ]; then
    cd ..
    rm -rf build
    mkdir build
    cd build
else
    echo "build directory DOES NOT exist"
fi

Every time you need to clean up, you should source this script from the build directory:

. cmake-clean-build

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If you have custom defines and want to save them before cleaning, run the following in your build directory:

sed -ne '/variable specified on the command line/{n;s/.*/-D \0 \\/;p}' CMakeCache.txt

Then create a new build directory (or remove the old build directory and recreate it) and finally run cmake with the arguments you'll get with the script above.

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If you run

cmake .

it will regenerate the CMake files. Which is necessary if you add a new file to a source folder that is selected by *.cc, for example.

While this isn't a "clean" per se, it does "clean" up the CMake files by regenerating the caches.

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cmake mostly cooks a Makefile, one could add rm to the clean PHONY.

For example,

[root@localhost hello]# ls
CMakeCache.txt  CMakeFiles  cmake_install.cmake  CMakeLists.txt  hello  Makefile  test
[root@localhost hello]# vi Makefile
clean:
        $(MAKE) -f CMakeFiles/Makefile2 clean
        rm   -rf   *.o   *~   .depend   .*.cmd   *.mod    *.ko   *.mod.c   .tmp_versions *.symvers *.d *.markers *.order   CMakeFiles  cmake_install.cmake  CMakeCache.txt  Makefile

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This is pretty old, but if you completely remove the cmake-build-debug folder, when you compile using cmake it should automatically create a new cmake-build-debug folder with everything you need. Works especially well in CLion.

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Here is what I use. It's wrapped in a function, It's cross platform and it demonstrated how to find matching filenames or folder names, in case you wanted to make any easy adjustments. This function runs every time I build my scripts and has worked flawlessly for my needs.

function(DELETE_CACHE)
    if(CMAKE_HOST_WIN32)
        execute_process(COMMAND cmd /c for /r %%i in (CMakeCache.*) do del "%%i" WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
        execute_process(COMMAND cmd /c for /d /r %%i in (*CMakeFiles*) do rd /s /q "%%i" WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
    else()
        execute_process(COMMAND find . -name "CMakeCache.*" -delete WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
        execute_process(COMMAND "rm -rf `find . -type d -name CMakeFiles`" WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
    endif()
endfunction()

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I used zsxwing's answer successfully to solve the following problem:

I have source that I build on multiple hosts (on a Raspberry Pi Linux board, on a VMware Linux virtual machine, etc.)

I have a Bash script that creates temporary directories based on the hostname of the machine like this:

# Get hostname to use as part of directory names
HOST_NAME=`uname -n`

# Create a temporary directory for cmake files so they don't
# end up all mixed up with the source.

TMP_DIR="cmake.tmp.$HOSTNAME"

if [ ! -e $TMP_DIR ] ; then
  echo "Creating directory for cmake tmp files : $TMP_DIR"
  mkdir $TMP_DIR
else
  echo "Reusing cmake tmp dir : $TMP_DIR"
fi

# Create makefiles with CMake
#
# Note: switch to the temporary dir and build parent 
#       which is a way of making cmake tmp files stay
#       out of the way.
#
# Note 2: to clean up cmake files, it is OK to
#        "rm -rf" the temporary directories

echo
echo Creating Makefiles with cmake ...

cd $TMP_DIR

cmake ..

# Run makefile (in temporary directory)

echo
echo Starting build ...

make

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Create a temporary build directory, for example, build_cmake. Hence all your build files will be inside this folder.

Then in your main CMake file add the below command.

add_custom_target(clean-all
    rm -rf *
)

Hence while compiling do

cmake ..

And to clean do:

make clean-all

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